Adjustable Die For Crank Threads

[chris-p]

Saw this on ebay. I have never used one, but imagine it would be handy for repairing damaged threads on the TOP of the crank for the flywheel nut from when dolts wail on them with a hammer! Sometimes, I find it difficult to get it started straight, as its always the first few threads that are shot. I wonder if this would allow you to start on the bottom of the thread, tighten the lock nut, then thread it back upwards, keeping everything straight….what thinks you wise men….

http://www.ebay.ca/itm/NOS-HANSON-ACE-9 … SwQaJXS8G1

[chris-p]

Actually don’t think that would work….I see they only provide a few thou adjustment, wont open enough to drop over the thread. Ah well.

[pm-t2]

to the best of my knowledge, these dies do have have the flexibility to be able to travel all the way over the damaged threads. The adjustability only equates to a range that might be several thousandths of an inch, but that’s all. They are hardened tool steel, and don’t have a lot of flex in them. We used to machined male threads in zinc with dies like that, but typically if we were adjusting it, the reason was to make the thread SMALLER as the cutting edges of the die started to wear.

A threading die will cut steel away and may cause you even MORE problems if you’re not careful with it.

For peened over threads such as you describe I keep thread files around, and use them to restore the original form of the thread as much as possible as a first step. This is followed by a "thread restorer" that rolls or forces the existing thread back into its proper profile without actually cutting any steel.

I’ve saved many crankshafts using the thread files and chasers, but there’s been many others that just had to be welded up and have the threads re-cut on a lathe.

Hope this helps eh.

Best,
Chris S

[chris-p]

Thanks Chris…..good to know. Ill look into getting a file and restorer.

[chris-p]

Found a few examples of thread restore. Learned something new today. Thanks. Have a rum n coke on me!

http://www.ebay.ca/itm/Jawco-455-Wheel- … SwxH1T0a8-

[amuller]

There are two-piece dies that can operate as you suggest, if you can get them below the buggered up part.

https://www.motionindustries.com/produc … u=03093007

And there are these, which I have not used but look well worked out: https://www.jmeinnovations.com/

If things are not too bad, it is possible to split a grade 8 nut, clamp it on with vise-grips, and work it up with the aid of something like moly grease.

Yr idea is sound–anything to avoid starting new threads from the top that don’t line up with the existing helix.

[mr-asa]

quote Chris_P:

Found a few examples of thread restore. Learned something new today. Thanks. Have a rum n coke on me!

http://www.ebay.ca/itm/Jawco-455-Wheel- … SwxH1T0a8-

I’ve never heard of those as thread restorers, I’ve seen them billed as thread chasers and cleaners, though

[crosbyman]

so what if you cut a nut in half and… re-spotweld it over the good part of a damaged thread then unscrew it upwards to clean up the damaged part ?

sorry guys it is 9;30 here no coffee or juice yet 😉

Joining AOMCI has priviledges 🙂

[RICHARD A. WHITE]

The nut would fail as it is the same hardness at the threads… to properly chase or "recut" threads the die must be harder that the threads you are trying to repair

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[dave-bernard]

break a die then use a vise grip to hold it in place under the damage and unscrew it.

[Author]

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